Anti-pick lock assembly

ABSTRACT

An anti-pick lock assembly in which the rotor of a tumbler lock is biased toward its locking position by a torsion spring. The spring bias force is sufficient to prevent the tumbler rotor from being set at a displacement within the working tolerance of the internal lock parts that allows the code pins to be manipulated one at a time into their release positions by a pick tool.

United States Patent [191 Greenwald ANTI-PICK LOCK ASSEMBLY [75] Inventor: Harry Greenwald, Whitestone, NY.

[73] Assignee: Walter Kidde & Company, llnc.,

Clifton, NJ.

[22] Filed: July 26, 1972 [21] Appl. No 275,218

[52] U.S. Cl 70/419, 70/DIG. 36, 292/37 [51] Int. Cl. E051!) 63/00 [58] Field of Search 70/419, DlG. 36, 70/363, 416, 85,86; 292/34, 37

[56] References Cited UNITED STATES PATENTS 1,309,439 7/1919 Keefer 70/4 C [451 Jan. 1974 Primary ExaminerRobert L. Wolfe Attorney-Irving Seidman et al.

[5 7] ABSTRACT An anti-pick lock assembly in which the rotor of a tumbler lock is biased toward its locking position by a torsion spring. The spring bias force is sufficient to prevent the tumbler rotor from being set at a displacement within the working tolerance of the internal lock parts that allows the code pins to be manipulated one at a time into their release positions by a pick tool.

2 Claims, 2 Drawing Figures ANTI-PICK LOCK ASSEMBLY BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates in general to lock devicesand more particularly to an anti-pick lock assembly in which a tumbler lock is resiliently biased against picking action.

I-leretofore tumbler locks, such as are commonly used on the coin boxes of vending machines and coinoperated appliances, have been vulnerable to picking. A technique frequently used by lock pickers was to maintain'the respective code pins set by applying a torque on the tumbler turning member until all code pins had been manipulated into their release positions by a pick tool. By doing this, a lock picker with an ordinary sense of touch could easily position each pin at its break free position so that the lock could be opened without a key. Generally, the movement allowed by the working tolerance of the component lock parts was sufficient to permit the picker to set free one or more of the code pins. By successfully performing operations a number of times, the picker could eventually set all pins and thereby open the lock.

The invention provides a spring that is coupled to the rotor output member of the tumbler lock so as to bias it towards its locking position. According to a preferred embodiment of the invention, the spring is arranged to give a preload return torque that is sufficient to overcome that which can be applied by a pick tool. In this way, the invention foils the lock picker by making it impossible to hold previously set pins in their break positions while the others are worked on in succession.

The presence of such preloaded spring tends to make it more difficult for the lock picker to sense by touch when a pin is set at break position.

One advantage of the invention is that it allows construction of pick-resistant locks without requiring closer, and more expensive, machining tolerances.

For a better understanding of the invention and its several advantages, reference should be had to the following detailed description and accompanying drawing which exemplify'a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWING 1n the drawing:

FIG. 1 is an elevation cross-sectional view of a lock assembly constructed in accordance with a preferred embodiment of the invention, and shown as installed in the cover door of a coin box.

FIG. 2 is a sectional view taken along line 2- 2 of FIG. 1 to show the back of the lock assembly and cover door.

DESCRIPTION OF A PREFERRED EMBODIMENT Y OF THE INVENTION In FIGS. 1 and 2 there is exemplified a lock assembly in which a tumbler lock unit 11 is received in a support means in the form of a cover door 12 for a coin box 13. Door 12 is connected as by screw fasteners 14 to a coin tray 15 that is slidably. received in coin box 13.

As better seen in FIG. 2, there are provided relatively movable lock members 16, 17 and 18 interconnected by slot-and-tongue means 19. When the central lock member 16 is displaced outwardly by the turning of a cam 20 in contact with edge 21, the lock members 17 and 18 are simultaneously driven outwardly by the inclined wedge action of means 19. The outwardly displaced positions shown in FIGS. 1 and 2 for lock members 16, 17, 18 can be considered as their locking positions since the members 16, 17, 13 overlap the back of a lip 22 of coin box 13 to prevent pull-out of door 12 and coin tray 15. The front of lip 22 abuts a flange 23 on door 12. The lock members 16, 17, 18 are so arranged that they can be drawn back inwardly to unlocking positions which allow pull-out of door 12 by turning cam 20 in contact with an opposite edge 24 on lock member 16.

Turning of cam 20 whether to effect locking and unlocking of door 12 is done by turning the rotor 31 of tumbler lock 11 relative to the body 32 thereof. Lock 11 is of prior art construction and is normally operated by a key (not shown) having a tubular code-milled sleeve that is received over a stud 33 pressed into a bore 34 of rotor 31 for rotation in unison therewith. As in typical tumbler lock construction, the rotor 31 is locked against rotation relative to body 32 by a plurality of code pin assemblies 35. Each code pin assembly 35 has a two-piece code pin 36 that is axially slidable in a passage 37 extending in rotor 31 and aligned with a guide 38 seated in body 32 and containing a spring 39. Pin 36 has an inner section 36A and a separate but abutting outer section 368, the relative lengths of which sections 36A, 368 can vary from one assembly 35 to another in accordance with the intended key code. When the proper key is inserted a corresponding milled surface on the key will engage the end of each pin section 36B and push the two sections 36A and 36B inward against spring 39 until the break plane 40 defined by the abutting ends of sections 36A, 36B is aligned with the interface plane 41 of rotor 31 and body 32. If the key is not the proper one, all of the code pins 36 will not be set at their respective break positions and the rotor 31 will not be free to turn.

It has been found that a tumbler lock 11 could be picked by applying a torque to rotor 31 to give a slight angular displacement within the internal working tolerances so that the friction on the pin section 36A is sufficient to overcome the force of spring 39, thereby allowing each code pin 36 to be set in succession by manipulating a pick tool (not shown), until all pins 36 were set at their break positions and rotor 31 could be turned.

Rotor 31 actually can be considered as the output member of lock 11 in that the rotary movement of rotor 31 is used to drive cam 20 and impart movement to lock members 16, 17, 16. For such purpose, rotor 31 is provided with an extending threaded shaft 43 having opposing flat sides -12, which shaft 418 is passed through a matching cross-section hole in cam 20 and secured to cam 20 by a nut 413. Conventional means, such as a plate having stop surfaces, are provided such that the rotary movement of rotor 31 is limited between one angular position that corresponds to the locked position, and a second angular position that corresponds to the unlocked position as referred to the lock members 16, 17, 18.

To prevent picking of the lock 11 as would allow operation thereof without a key, the invention provides resilient means in the form of a spring 45 that biases rotor 31 for return movement to its locked position upon displacement therefrom toward its unlocked position. Spring 45 is expediently a coil spring, one end of which is received in a pocket 16 within door 12, and

the other end of which is received in a notched arm 47 of cam 20. While spring 45 is not connected directly to rotor 31, it is in actuality coupled thereto so as to exert thereon a biasing torque. Preferably, spring 45 is compressed between the support door pocket 46 and arm 47 of cam so that there is a preload return torque applied to rotor 31 that is greater than any torque that could be applied by a conventional pick tool. This assures that upon attempting to set up successive code pins 36, the lock picker will not be able to keep any previously set pins 36 at their break positions while working on a next pin 36.

it will be understood by the artisan that the specific spring 45 arrangement shown in the drawing represents only one example of the basic concept of the invention, and other resilient biasing spring arrangements that will bias rotor 31 for return to its locked position can be substituted.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be readily understood and appreciated that various changes or modifications thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

1. An anti-pick lock assembly which comprises in combination a tumbler lock means in which an output member is secured in a locked position by the action of code pins and is moveable to an unlocked position by the action of an associated key; a door receiving and supporting said tumbler lock means; a plurality of lock members supported by said door and interconnected by slot-and tongue means for movement in unison between respective locking positions and unlocking positions to correspondingly lock and unlock the door; a cam connected to said output member for rotation thereby and therewith, said cam being disposed for engagement with one of said lock members to move all of said lock members in unison in accordance with the movement of the output member, to position all lock members in their respective locking positions when the output member is at its locked position and to position all lock members in their respective unlocking positions when the output member is at its unlocked position; and a spring compressed between said door and said cam to exert a preload torque upon the output member biasing said output member for return movement to its locked position upon displacement therefrom toward its unlocked position.

2. An anti-pick lock assembly according to claim 1 wherein the lock member engaged by said cam has an opening defining an edge, and said cam is disposed for contact with said edge. 

1. An anti-pick lock assembly which comprises in combination a tumbler lock means in which an output member is secured in a locked position by the action of code pins and is moveable to an unlocked position by the action of an associated key; a door receiving and supporting said tumbler lock means; a plurality of lock members supported by said door and interconnected by slotand tongue means for movement in unison between respective locking positions and unlocking positions to correspondingly lock and unlock the door; a cam connected to said output member for rotation thereby and therewith, said cam being disposed for engagement with one of said lock members to move all of said lock members in unison in accordance with the movement of the output member, to position all lock members in their respective locking positions when the output member is at its locked position and to position all lock members in their respective unlocking positions when the output member is at its unlocked position; and a spring compressed between said door and said cam to exert a preload torque upon the output member biasing said output member for return movement to its locked position upon displacement therefrom toward its unlocked position.
 2. An anti-pick lock assembly according to claim 1 wherein the lock member engaged by said cam has an opening defining an edge, and said cam is disposed for contact with said edge. 